Problem: Ashley is 3 times as old as Michael and is also 4 years older than Michael. How old is Michael?
Solution: We can use the given information to write down two equations that describe the ages of Ashley and Michael. Let Ashley's current age be $a$ and Michael's current age be $m$ $a = 3m$ $a = m + 4$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $m$ , and both of our equations have $a$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $3m$ $-$ $ (m + 4)$ which combines the information about $m$ from both of our original equations. Solving for $m$ , we get: $2 m = 4$ $m = 2$.